Shade or blind assemblies used with windows or similar openings are well known. The assemblies provide for privacy when desired and block sunlight or allow sunlight to enter a room. Many types of shades are configured with vertical or horizontal slats that are raised and lowered, or moved sideways, by a chord wherein the angular position adjustment of the slats can also be provided. Both adjustments can be automated or manually implemented.
In some shade assemblies it is desired to provide motorized operation of the shade. This allows for convenient and automated control of the shade assembly. In other words, the shade assemblies can be programmed to open and close at particular times of day or evening so as to let in sunlight when desired or block sunlight when heat in the room becomes uncomfortable. In any event, to assist in operation of the shade assembly, the internal mechanism for raising and lowering of the shade may incorporate a counterbalance assembly. The counterbalance assembly, which usually includes a spring, is utilized to compensate for the weight of the shade and reduces strain on the motor, if provided. The counterbalance spring may be pre-tensioned so as to prevent excessive current draw by the motor which drains the battery more quickly and causes the motor to wear prematurely.
In order to provide for tensioning in prior art shade assemblies it is common to hold the tension and stored potential energy with shear pins as a means to trigger a release event when thresholds are met. These thresholds may be used for safety purposes or to prevent the transmission of undesired forces, but they do not allow further tension adjustments of the counterbalance spring, which many times is needed to achieve optimum counterbalancing. Indeed, it is well known in the prior art to provide counterbalancing systems, but none provide for pre-tensioning of the counterbalance system.
Therefore, there is a need in the art to provide a gear tensioner and related method of installation to store tension in a shade or blind assembly such that the assembly is pre-tensioned at the factory, the point of shade or blind assembly, or during installation of the shade or blind. Further, because a torque profile of counterbalance springs does not always precisely match the force requirement of the roll shade being payed out or reeled on to a storage roll, there is a need to be able to set various pre-tension values on the counterbalance springs. Moreover, there is a need to minimize drag on a motor utilized to raise and lower the shade assembly, thereby extending battery life.